1. Field of the Invention
The present invention relates to a light emitting diode used in a device such as a personal computer, printer, PDA, facsimile, pager, mobile phone or the like.
2. Description of Related Art
Recently, a liquid crystal display having a thin and visible backlight mechanism is widely used for various electrical devices of a mobile device and so on, such as a laptop personal computer, PDA, mobile phone or the like, on which light communication functions are loaded.
Conventionally, a surface-mounted light emitting diode provided for small and thin electronic devices has usually a structure in which a pair of electrodes are patterned on an upper surface of a glass epoxy substrate, an LED chip is fixed on the electrodes by a transparent adhesive, upper electrodes of the LED chip and the pair of electrodes on the substrate are wire-bonded, and a transparent resin is attached to the substrate to cover the LED chip.
The light emitting diode having such a structure has low usability of light, because it has no reflector part and light emitted from the LED chip radiates from a side surface of the transparent resin.
Therefore, a light emitting diode, in which the usability of light emitted from the LED chip is improved, is widely used, for example, as shown in Japanese Patent Laid-Open 2002-280614.
The light emitting diode 21 described in the patent document as described above has a structure in which an insulative substrate 24 is formed by insert molding of a white resin and silver-plating electrode patterns are disposed on the substrate 24, an LED chip 26 is fixed on the electrode patterns 22,23 by a transparent adhesive 25 and upper electrodes (not shown) of the LED chip 26 and the electrode patterns 22,23 are connected by bonding wires 27 comprising metal thin wires, and a reflective member 28 having a reflector part 28a which has an upward parabola shape is disposed on the insulative substrate 24 so as to surround the LED chip 26.
A transparent resin 29 is also disposed within the reflector part 28a to cover the LED chip 26.
The light emitting diode 21 structured as described above is surface-mounted on a printed substrate 19 by soldering 20.
The light from upper and side surfaces of the LED chip 26 is reflected on the reflector part 28a and emitted upwardly, however, there is a problem that light emitted from a lower surface of the LED chip 26 is blocked by the electrode patterns 22, 23 or the insulative substrate 24. As a result, the light emitted from the lower surface of the LED chip 26 cannot be used efficiently and the light loss of the LED chip 26 becomes large.